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Tag: surface tension

Q.1 A piece of copper having internal cavity weighs 264g in air and 221g in water. Density of copper is 8.8gm/cm3. The volume of cavity is

[a] 43cc [b] 30cc

[c] 13cc [d] 23cc

Q.2 A piece of brass [ alloy of copper and zinc] weighs 12.9g in air. When completely immersed in water it weighs 11.3g. Specific gravities of copper and zinc are 8.9 and 7.1 respectively. The mass of copper in the alloy is

[a] 11.3g [b] 9.61g

[c] 7.61g [d] 8.71g

Q.3 Water is flowing in a river. If the velocity of a layer at a distance of 10cm from the bottom is 30cm/s. The velocity of a layer at a distance of 30cm from the bottom is

[a] 30cm/s [b] 45cm/s

[c] 60cm/s [d] 90cm/s

Q.4 If one end of the capillary tube of radius r when kept in water vertically, the rise in water level is 6cm. The rise of water in capillary tube of length 20cm whose radius is 1/4th of the original capillary tube is

[a] 24cm [b] 18cm

[c] 22cm [d] none of these

Q.5 An ice cube of volume 1m3is kept in gravity free space. When ice melts the surface area of ice is

[a] [9?]1/3 [b] [18?]1/3

[c] [36?]1/3 [d] [27?]1/3

Q.6 Calculate the force of attraction between the two parallel plates separated by a distance of 0.2mm after a water drop of mass 80mg is introduced between them. The wetting is assumed to be complete [Surface tension of water is 0.07Nm-1]

[a] 0.14N [b] 0.28N

[c] 0.42N [d] 0.56N

Q.7 Which of the following graphs can possibly describe the motion of solid sphere in a viscous liquid?

[a] 1

[b] 2

[c] 3

[d]4

Q.8 A vessel contains water upto a height of ?3 / 5m. The vessel is accelerated to the right at 10/?3 m/s2. Find the maximum height by which water level rises from the original height is

[a] 0.5m [b] 1/?3 m

[c] 1m [d] 0.6m

Q.9 A rod of density ? is pivoted to the wall of a tank filled with water such that certain portion of it is under water. The fraction immersed is

[a] 1- [?/?]

[b] [- [?/?]1/2

[c] [1- (?/?)]1/2 [d] 1- [1- (?/?)]1/2

Q.10 Two identical holes each of cross sectional area 2mm2 are opened on the diametrically opposite sides of a wide tank filled with water. The difference in height of 2 holes is 50cm. The resultant reaction R to the flow is

[a] 0.06N [b] 0.05N

[c] 0.02N [d] 0.07N

Q.11 A hollow sphere of radius 10cm is made of metal whose specific gravity is 100/27. The sphere will float in water only if the thickness of the wall of the sphere is less than:

[a] 1cm [b] 0.5cm

[c] 0.7cm [d] 0.375cm

Q.12 A body of density 0.65gm/cm3 is dropped from rest from a height of 3m into a pond of water. The depth to which the body sinks before coming to the surface is

[a] 5.1m [b] 5m

[c] 5.6m [d] 5.8m

Q.13 A liquid of specific gravity 0.8 is kept in a cylindrical vessel which rotates about its own axis at 1 rev/s. if the radius of the vessel is 6c,, then difference in height of liquid at the center and on the sides is

[a] 7.1mm [b] 3.5mm

[c] 14.2mm [d] 5mm

Q.14 A beaker containing liquid of density 0.85gm/cm3 moves vertically upwards with acceleration of 3m/s2. The radius of the beaker is 7cm and the height of liquid is 18cm. The pressure at its base is

[a] 0.2kPa [b] 2kPa

[c] 2.35kPa [d] 1.5kPa

Q.15 A cubic block of side 10cm and density 0.5gm/cm3 is supported on a spring of spring constant 100N/m. The spring is surrounded by water surface and water surface is just in contact with the lower face of cubical block. The force applied normal to the top face so that the block gets completely immersed in water is

[a] 15N [b] 5N

[c] zero [d] 20N

Q.16 Energy required to split a liquid drop of radius 1cm into 27 identical droplets is

[a] 2?T x 10-4J [b] 4?T x 10-4J

[c] 6?T x 10-4J [d] 8?T x 10-4J

Q.17 Water is flowing with a speed of 5.18m/s through a pipe of cross sectional area 4.2cm2. The water gradually descends 9.66m as the pipe area increases to 7.6cm2. The speed of flow at lower level is

[a] 3m/s [b] 5.7m/s

[c] 3.82m/s [d] 2.86m/s

Q.18 The terminal speed of a sphere of gold [specific gravity 19.5] is 0.2m/s in a viscous medium of density 1500 kg/m3, find the terminal speed of silver [specific gravity 10.5] of same size in the same liquid

[a] 0.4m/s [b] 0.133m/s

[c] 0.1m/s [d] 0.2m/s

Q.20 Water flows in streamline manner through a capillary tube of radius ‘a’. The pressure difference is p and the rate of flow is Q. if the radius is reduced to a/2 and pressure difference is increased to 2p, then the rate of flow is

[a] 4Q [b] Q

[c] Q/2 [d] Q/8

Q.21 By inserting a long capillary tube upto depth l in water, the water rises to height h. If the lower end of the tube is closed inside water and the capillary is taken out and closed end opened, the length of water column in the tube is

[a] zero [b] l+h

[c] 2h [d] h

Assertion Reasoning Questions

[a] Both A and R are true and R is correct explanation of A

[b] Both A and R are true but R is not correct explanation of A

[c] A is true , R is false

[d] A is false, R is true

Q.22 A: When two bodies sail parallel in the same direction and close to each other, they are pulled towards each other

R: The viscous drag on a spherical body is proportional to the speed.

Q.23 A:A steel blade placed gently on the water floats on it

R: Buoyany force of water is equal to the weight of the blade

Q.24 A:With the increase in temperature viscosity of gas increases

R: With the increase in temperature collisions between the molecules of the gas increases

Q.25 A: AT critical temperature, the surface tension of the liquid becomes zero.

R: At this temperature, intermolecular forces for liquids and gases becomes equal.